This invention relates to drums or barrels. More particularly it relates to plastic drums with drum inserts for accessing the fluid in the drum and closures for same.
Steel and plastic drums are utilized in many industries for transporting and storing various liquids which may be utilized as fuels, lubricants, ingredients, process fluids, or the like. Often the liquids transported and stored in such drums are highly caustic and/or hazardous and absolute containment during storage, transport, and handling are essential. For example in the semiconductor industry, caustic chemicals such as hydrofluoric acid are commonplace. Some liquids develop significant internal gas pressures when contained during storage. Such pressures must be periodically vented. Even when drums with such hazardous and caustic liquids are on site and ready for use, great care must be taken in accessing the liquids so as not to expose personnel or the environment to such chemicals.
Plastic drums utilized in the semiconductor processing industry typically have standardized openings on the top of the drums. These openings comprise a pair of ports or bungholes, each having a fitting with a neck extending upward from the top wall of the drum approximately 1 to 11/2 inches. The ports each have 2 inch internal buttress threads. Several closures or bungs may be utilized with these standardized ports including standard bung closures which are threadedly inserted into the openings and which engage with the top shoulder of the neck. These standard bung closures extend a fraction of an inch above the neck.
Access to the liquids in the plastic drums is typically accomplished by multiple port bung connectors which attach to drum inserts such as disclosed in U.S. Pat. No. 4,699,298, issued to Grant, et al, and assigned to FSI International Corporation and as disclosed in U.S. Pat. No. 5,108,015, issued to Rauworth, the inventor in the instant application with the same assignee, Fluoroware, Inc. These patents are hereby incorporated by reference. The bung connectors illustrated in these patents have drum inserts with down hole tubes extending to the inside bottom of the drums for withdrawing the liquid in the drum and for providing a means for sensing the level of the liquid in the drum. An additional tube or port in the insert is utilized for supplying air or other gas to replace the liquid as it is withdrawn. The drum insert is threadably engaged to one of the ports at the buttress threads in place of and in the same fashion as a standard bung closure. The drum insert has external threads to engage the multiple port bung connector head which will have lines to the processing equipment or other storage containers.
The drum inserts, as disclosed in Grant and Rauworth patents extend above the shoulder of the neck of the drum port into which they are installed approximately 3/8 to 1/2 of an inch. Closures for the drum inserts to be used when the multiple port bung connector head is not in place are configured in several different ways. For example the closure of FIG. 5 includes a vent connection port and a valve for venting internal drum pressure. Each configuration of closures add an inch to an inch and 1/4.
To aid in handling steel and plastic drums, protruding annular lips, commonly termed "chimes", will typically be an integral part of or an attached part of the drums. The chimes extend upwardly at the top and downwardly at the bottom of the drums. The chimes provide a grasping lip which is gripped by mechanized handling equipment equipped with a "parrot beak".
Drums may be stacked either with pallets or other spacers intermediate vertically adjacent drums or the drums may simply be stacked on top of one another. The chime at the top of the drum also provides protection to the top ports and connectors, particularly when the drums are stacked. The top of the chime needs to extend above the ports and connectors to provide this protection. Known existing drums with integral chimes extend at most, only a fraction of an inch above the shoulder of each neck at the drum ports. Although plastic composite drums are known which utilize a separate chime portion attached to the top of the drum and which are positioned high enough off the top of the drum such that the various known closures do not extend thereabove, the prior art does not disclose such a drum with an integral top structure.